we use special cuvettes to hold samples of interest in the spectrophotometer cuvettes are made of thin uniform glass or plastic that is highly transparent to light at wavelengths used (some wavelengths such as those in the ultraviolet region (200 to 300 nm) require cuvettes made of other materials such as quartz) since cuvettes can be very expensive all cuvettes should be handled very carefully so they are not scratched or broken do not put anything sharp or hard into a cuvette when you use them always position them such that the light passes through the optical windows and not the sides of the cuvette intended for your fingers rinse your cuvettes with distilled water immediately after use to prevent materials from drying onto the inner surfaces